Boat Capacity Calculator
Fill in the values and the answer updates as you type.
How the Boat Capacity Calculator works
A common rule of thumb for monohull boats under 20 ft is people = boat length × beam (both in feet) ÷ 15, rounded down. Total load is the people at your average weight plus the motor and gear. It follows the idea behind the capacity plate of the US Coast Guard, but it is not a legal rating. Always obey the capacity plate on your boat, and carry fewer people in rough water, in cold weather, or when the load is uneven. The result is for planning only. Example: with Boat length 16 ft, Boat beam 6 ft, Average person weight 150 lb, and Motor and gear weight 350 lb, the result is People the boat can carry = 6; Unrounded result = 6.4; Total load: people, motor, and gear (lb) = 1,250.
Inputs and results
The Boat Capacity Calculator takes 4 inputs and gives 4 results.
What you enter
- Boat length (ft) — starts at 16.
- Boat beam (ft) — starts at 6.
- Average person weight (lb) — starts at 150.
- Motor and gear weight (lb) — starts at 350.
What you get
- People the boat can carry
- Unrounded result
- Total load: people, motor, and gear (lb)
- Rule status
Example: Boat Capacity Calculator with the starting values
With boat length 16 ft, boat beam 6 ft, average person weight 150 lb and motor and gear weight 350 lb, the calculator returns:
| People the boat can carry | 6 |
|---|---|
| Unrounded result | 6.4 |
| Total load: people, motor, and gear (lb) | 1,250 |
| Rule status | Within the under-20-ft rule of thumb |
Change any value above and the results update straight away.
Boat Capacity Calculator FAQ
How do I use the Boat Capacity Calculator?
Enter boat length, boat beam, average person weight and motor and gear weight in the fields, then read people the boat can carry, unrounded result, total load: people, motor, and gear (lb) and rule status in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Boat Capacity Calculator calculate?
Rule of thumb for the number of people a small boat can carry. It returns people the boat can carry, unrounded result, total load: people, motor, and gear (lb) and rule status from the 4 values you provide.
What values does the Boat Capacity Calculator start with?
It opens with boat length 16 ft, boat beam 6 ft, average person weight 150 lb and motor and gear weight 350 lb so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Boat Capacity Calculator free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Boat Capacity Calculator for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.